Pneumatic hammer



J. T.l McGRA-FH PNEUMATIC HAMMER April 1, 1930.

Fild March 5, 1929 INVENTOR J. T. MC @en TH ATTORNEY e Pneumatic hammers are used lfor many between the vertical supports of the casing 50 Patented Apr. 1, 1930 i 7 l UNITED STATES PATENT OFFICE Application filed March 5, 192B. Serial No. 344,155.

. This invention relates to4 improvements in cylinder casing 2 of the hammer within pneumatic hammers and more particularly which the piston 3 is mounted for reciprocato an improved valve for controllingy the extion. The piston rod passes through the haust in such devices.A bottom of the cylinder casing and is extended purposes and are yboth portable and station- 2. In this form of hammer the lower die ary. This invention relates to the stationary .5 is held in fixed relation upon the base 1 type land it is an object of this improved valve between the lower ends of the vertical supconstructionto increase the eihciency of the ports for the piston casing and the upper 1n hammer and economize in the air-under presdie 6 is secured to the lower end of the piston 55 sure required for its operation. rod 4 and is mounted for reciprocation there- With theseand other objects in view, refwith upon guides 7 upon the inner sides of erence is made to the accompanying sheet of said cylinder supports. A cylinder head 8 is drawing which illustrates a preferred form Vbolted to the cylinder casing 2 and forms an D of this invention with the understanding that .extension of the cylinder 9within which the 60 jminor detail changesmay be made without Vpiston 3 reciprocates. L departing from, the scope thereof. Y The piston 3 is of the hollow type, that is, In the drawings: v y the piston 3 and `rod 4 depending therefrom VFigure 1 is a view in front elevation, with are provided with a central cylindrical cav- 20 parts illustrated in central vertical section. ity 10 and the piston vhead is tapered, as 55 Figure 2 is a detail view infront elevashown, with-a piston ring 11 about the piston tion of the stationary member of the exhaust below the tapered portion. About the cylingvalvevmechanism. y Y l der head 8 a plurality of air valvesV 12 are Figure 3 is a detail View in front elevation provided having stems entering the 4cylinder 25 of sliding member of the exhaust valve mechand adapted to be engaged and be moved 70 anism. y H outwardly by the tapered portion of the Dis- The improved valve is illustrated as em- -ton 3 upon the up stroke touncover air ports bodied ina pneumatic hammer of the sta- 13 leading from an air conduit 1-1 formed in tionary type such as employed as apart of Ythe cylinder casing 2. The conduit 14 comso theequipmentof the lue department of a municates with an air inlet 15 leading up- 75 railroad repair shop, although this improved ward from the bottom of the cylinder 9 at valve may be employed in pneumatic hamwhich point it opens into said cylinder mersconstructed for other purposes. Furthrough a port 16, opposite this point said thermore, the part illustrated in Figure 1 is inlet15 is connected to an air pipe 17 from 35 the moving and working parts of the hama source of air under pressure, not shown. so mer lonly which in practice is usually mounted The central cavity 10 is provided with one on astand or support, not shown. The paror more ports 18 in the piston rod 4 which ticular hammer illustrated is designed for are normally closed by the bottom of the use in welding and swedging the .safe ends cylinder casing 2 during the upper move- 40 onf1oco motive boiler flue tubes. r ments of the piston and during the lower S5 As shown' in Figure '1, the body or base 1 movements are uncovered to the atmosphere isladaptedto be rigidly secured to a'support into which the air confined by the upward not shown, and includes two oppositely disstroke of the piston may escape or exhaust. posed parallel vertical members Vbrought to- The passage of airthrough the pipe 17 45. gether at the top to engage and support the from thesource ofcompression may be regu- 9o lated by a valve, not shown, of any desired type, for instance one operated by a foot treadle, and when opened the operation of the hammer is continuous until the valve is again closed. The air under compression entering from pipe 17 passes through port 16 into the cylinder 9 below the piston 3 causing it to move upwardly, at the same time the air passes through intake 15 to conduit 14 to the closed valves 12. As the piston 3 approaches the upper limit of its travel the tapered piston head engages and opens val-ves 12 -iilling the cylinder `9 above the piston 3 and the central cylindrical cavity 10 causing .the piston 3 to descend, and, in descending, the exhaust ports from'the Acavity 10 Vare'unc`overed allowing the compressed air ftoexhaust, the valve 12 having closed as the tapered niston head descends. Y,

The above described construct-ion and operation is othe general type lfor pneumatic hammers of this general character `and `is necessary to illustratethe-advantages ofthe improved valve mechanism now to be described.

A hollow cylindrical `member A2O, of less diameter than that of the cavity l10,a`ntl -having a horizontally extendingflange 21l about itslower openend toi snuglybe received withstanding flange-23 aboutl its lower endadapted to engage and rest upon `the top of the piston -head about the cavity 1() which Asleeve travels 4up and down about the member 20 as the piston 3 reciprocates. The stationary member 2O is provided with afseries-ofgraduated exhaust ports 244 about itsfcircumference so arran ed-that at the endof the downfstroke all will e-uncovered bythe sleeve 22 allowing-the compressed air int-he cylinder-9 above the Ypistontoexhaustthrough all of the ports 24, through cavity 10, and `Aports l-Stothefatmosphere, and Ito be gradually `closed `as'the piston moves upward -until thelsleeveV -22' covers them all as the upper limit ot'fthepiston movement is reached, and the valves -12are completely opened.

In this construction the cylinder head 8 carries all ofthe valves includingthe slid-ing sleeve valve 23, as thellange 21 on'the -st'ationary memberQO-engages the bottomof the sleeve 22. Thehead 8- is-preferably-secured to the cylindercasi-n'g 2-by a seriesof bolts, as shown, which f boltsV mayv be circumferentially undercut Y where v they pass through'fthe air conduit 14 lto allow direc passage Ttherethrough. Y

It is readily seen`from` the operation ofthe sliding sleevevalve that the compressed air admitted through ports 12 into the cylinder 9 above the piston acts immediately upon' the piston more quickly than if it had to first lill the cavity 10 in the piston and piston rod and the hammer is more eflicient and consumes less air and is therefore more economical than a hammer of the same type without the improved sliding sleeve valve mecha- IIISID.

What I claim is:

l. In a pneumatic hammer comprising a closed cylinder, a piston mounted for reciprocation therein, a piston rod thereon passing through one :end of v'the cylinder, la central cavity formed insaitl --piston and plston rod .opening through said piston into the cylinder thereabove and having a port in Said piston rod adapted to'eiliaust into the at- --mosphereas the piston rod approaches the outward limit of its stroke, normally closed automatic airfinlet valves between the open side of the piston and adjacent end of the fcylinderadapted -to be=petied the lpiston approaching that end of Athefcylinder1in-its 'upward stroke and f-anair portopnin'g the cylinder on the other'fside lof-the adjacent that endlof they oylinderf-andlitieans 'connecting said lair'iinlet andalr to a source VofL afi-runder pressure; theckbinaten with an automaticeXlraustfval-ve betweenlftle piston cavity @and the adjacent *end "of the piston, including astationaryhollow member entering thepisten-cavi-ty and' asleevelmounted to f reciprocate thereon with the pistn.

` closed cylinder, `'a pistonlmounted'for reciprolcation ltherein, a fpistonirodthereon passing through end :of the cylinder, la 'central outward limitI 'ofitsfstrokefnormally'closed automatic air inlet valvesfbetwe'rnthepen Aside of the pist'onancl adjaeentfendeof-Jthelcylindrf'adapted -to-beo erred b approaching that end o the cy inder infits-upward: strokelandf an afirportopening into the cylinder 'onf' the other liside -of -the'-l piston aldj acent `that endv of lthe cylinder,- andfnea'nsoom neetin'g-said air inlet and airportltofasource ofair vunder pressure, th'e'fcombinat/ion #with iain' automatic -eahaust valvebetween' thep'iston "cavity and the?v adacent end ofthe-pistoni cluding a= stationary hollow lentnfilg the piston eavityiand -proviied'withpo'rts there about efmimunicatin'giwitfh lthel cylinder and-- a sleeve mounted-upon saild fn'lemlaerto reciprocate with tliepiStnteeOvr axidfuncover perte.

3. In a pneumaticm" 'er-"eo'mpmsi` ng'a cylinder *and a reeiprcating hollow lpiston and 1 'pistn Lrod opera .am :um lm eyiaaer Vthrough 'the f pist/on@ `5to the 'atmosphere underpressure to the cylinderon sidesiopposite the piston, in combination with an exhaust valve within the cylinder having a hollow member adapted to be received in the hollow piston secured to end of the cylinder and provided with a plurality of ports about its circumference and a sleeve mounted to travel upon said stationary member provided with means adapted to be engaged by the piston and cause the sleeve to reciprocate therewith, said ports in the stationary member arranged to be successively uncovered by the sleeve as the piston departs from the stationary member and successivel covered as the piston approaches the end o the cylinder.A

JOHN THOMAS McGRATH. 

